^^ Celacanthcs. 



velopment, and it is only by diminishing in all directions that 

 it at last reaches its point of extinction in the chalk. If we 

 wish to represent it graphically, it may be regarded as a cone, 

 with a broad base, the smurait of which is formed by the 

 genus Macropoma, while at the base are found the Holopty- 

 chius, Phyllolepis, Glyptolepis, Platygnathes, Dendrodus, Lam- 

 nodus, Cricodus, Asterolepis, Bothriolepis, Psammosteus, &c., 

 of the Devonian system ; all as remarkable by their structure 

 as by the numerous individuals whose remains are every- 

 where found in this formation. Indeed, if there be one fact 

 that can prove how far it is true that ancient strata enclose 

 types in general less different than those of the present crea- 

 tion, but, by way of recompense, an infinitely greater num- 

 ber of individuals, it is surely this, that there are strata of 

 old red sandstone, particularly in Russia, which are nothing 

 else than true breccias, almost solely composed of scales and 

 plates of Asterolepis or Bothriolepis. If the Pterichthys 

 are so abundant in the nodules of Lethen-Bar that they are 

 collected in cartfuls, there is in this nothing surprising, be- 

 cause they were small fishes, living probably in shoals in the 

 mud, feeding, from all that we can gather from what is 

 known of their organization, on shell-less molluscs, vermes, 

 and other unprotected animals. But when we remember 

 that the Bothriolepis and Asterolepis were fishes of very con- 

 siderable size, eminently rapacious, and feeding, to judge 

 from their dentition, on living prej^ we will consider it very 

 surprising that these voracious species, whose analogues of 

 our own day are always found widely scattered, should be 

 assembled in such great numbers as is the case in certain 

 localities. 



What is very curious in the Celacanthes of the old red 

 sandstone is, that we already encounter in its numerous 

 genera many pretty distinct types. These are, on the one 

 hand, the Glyptolepis, which, by their double fins, make so 

 near an approach to the Dipterian Sauroides that one may 

 believe in a certain parallelism between the two families ; 

 on the other hand, the Asterolepis (Dendrodus), the Bothrio- 

 lepis, and the Psammosteus, the characteristic scales of 

 which have not yet been found, but which were provided with 



